A device for detecting a chewing action has been conventionally proposed.
When a person masticates a food and the like, a muscle of an external auditory meatus moves along with a move of a jaw. A device disclosed in Patent Document 1 detects a pressure change in the external auditory meatus resulted from this movement of the muscle by a pressure sensor inserted in the external auditory meatus to measure the number of the pressure change as the masticating number.
While a device disclosed in Patent Document 2 measures the masticating number using a similar principle, it describes that a low pressure sensor, a piezoelectric sensor and a press sensor are used as pressure sensors.
While an input device proposed in Patent Document 3 recognizes a state of a countenance, it is described that the input device can also detect a chewing action based on an output of an optical sensor attached to an external ear.